A New Method to Improve the Transient Performance of Virtual Synchronous Generator with the Extended Virtual Impedance

Although the virtual rotor inertia and damping factor in the virtual synchronous generator (VSG) control can reduce the rate of change of frequency (ROCOF) in the inverter stand-alone mode and contributes to overall frequency stability in the grid-connected mode, they deteriorate transient performance in the grid-connected mode with power/current overshoots and oscillations. In this paper, an extended virtual impedance method is introduced for the first time to improve the transient performance of the VSG active power loop. Compared to the existing solutions, the proposed method achieves more exceptional transient performance in the grid-connected mode with the simpler parameter tuning process. Meanwhile, it also keeps the effective rotor inertia unchanged and maintains the same frequency stability in the grid-connected or stand-alone modes. Finally, the effectiveness of the proposed method is validated and compared with existing method by experimental results.